This invention relates to closures for threaded couplings and more particularly to a terminator and lock for a female coaxial plug, such as is used in cable television systems (CATV), multipoint distribution systems, subscription television (STV) and master antenna TV systems (MATV).
It is a conventional practice in cable television systems to permit a plurality of individual subscribers to be connected to a single signal-carrying coaxial cable. Conventionally, this is accomplished by connecting the cable to a transformer or other impedance-matching/amplifying device which has a plurality of output ports. Each output port is usually a female coaxial plug. A cable can then be routed from each of these female coaxial plugs to a receiver unit of a subscriber to the signal-carrying system.
In such systems it is possible that the number of subscribers will at times be less than the number of female coaxial plugs which are provided on, e.g., a signal splitter, coupler, wall-plate termination and multi-taps. Under such circumstances it is then desirable to terminate each plug with an impedance that will match the impedance of the coaxial cable. This prevents an impedance mismatch between the signal-carrying cable and any subscriber cables that are connected, and can be accomplished by using a conventional male coaxial plug in which an impedance device such as a resistor is connected across the male coaxial plug.
A problem has arisen with regard to such terminated plugs. It has been found that non-subscribers to, e.g., a cable television network have attempted to steal the services of the network by removing the male coaxial terminator plugs, and connecting their own illegal coaxial cables to the female coaxial plugs, and failing to tender payment to the network.
It is known to provide tamper-resistant devices for terminating female coaxial plugs. Such a device is threaded onto the female coaxial plug and can be removed by using a special tool which is posessed by certain employees of the subscriber system.
Another problem encountered by, e.g., cable television networks is the problem of subscriber disconnection. If a coaxial cable has been once connected to a subscriber's location, and service is later terminated, it is possible to disconnect the subscriber's cable and to terminate the female coaxial plug to which the cable was previously connected. This leaves an obviously disconnected cable hanging unattached. A disconnected subscriber may then without the permission of the signal carrier proceed to remove the terminating device and reattach the coaxial cable to the female coaxial plug.
In prior-art plug terminating devices, the tool used to remove the tamper-resistant device has delicate moving parts such as springs, ball-bearings, etc. Such tools have a tendency to fail in use. Moreover, the prior art coupling devices use machined parts which are relatively expensive to manufacture. Furthermore, the assembly of the parts of such tools can also be relatively expensive.
An object of the invention is to provide a rugged tamper-resistant closure device for terminating a female coaxial plug.
Another object is to provide such a device which is operable by a tool having no moving parts.
It is another object of the invention to provide a device of this type which would be resistant to tampering by intruders in possession of commonly-available implements and items, such as screwdrivers, wrenches and the like.